1. Field of the Invention
The invention pertains to an electrohydraulic servo door drive for operating a door, a window, etc., with a hold-open function, where a valve is installed in the hydraulic circuit to implement the hold-open function.
2. Description of the Related Art
A servo door drive of this type is well known. The hold-open function of the servo door drive is usually achieved by means of a solenoid valve, which prevents hydraulic fluid from escaping from the piston space of the servo door drive. The disadvantages of this type of design are the amount of space required for it and the additional cost.